The European Space Agency’s (ESA) Gaia spacecraft will end its observations this week as it runs out of cold gas propellant.
Gaia space telescope aimed to create an accurate and detailed 3D map of billions of stars in our galaxy and has flipped astronomers’ understanding of the Milky Way on its head.
After more than a decade of mapping the stars and expanding our understanding of the cosmos, Gaia will shut down on 15 January after its cold gas – which decreases by about a dozen grams per day – runs out.
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The Gaia space observatory orbits the so-called Lagrange 2 (L2) point, approximately 1.5 million kilometres away from the Earth where gravitational forces between the Earth and Sun are balanced and unobstructed views of the sky can be observed, according to the University of Leicester.
The ESA says Gaia has been mapping the motions, luminosity, temperature and composition of stars in the Milky Way since its launch in December 2013 to create a ‘huge stellar census’.
The Gaia science observations will end on 15 January 2025, so no more science data will be acquired by Gaia after this week.
The ESA will conduct technology tests for several weeks after Gaia’s observations end, before the spacecraft leaves its orbit to enter its final heliocentric orbit. Gaia will ‘retire’ in March/April 2025 when it is passivated (internal energy is removed to reduce the risk of explosions or fragmentations).
The ESA says Gaia Data Release 4, which will include a larger data volume and better data quality than Gaia Data Release 3, is expected in 2026.
In its ‘groundbreaking’ mission, Gaia has answered important questions related to the origin, structure and evolutionary history of our galaxy.
Gaia has transformed astronomers’ understanding of the Milky Way -Credit:PA
“Gaia’s discoveries represent a step change in how we understand the Milky Way. It’s astonishing what this mission has discovered in a relatively short space of time,” said Timo Prusti, Project Scientist for Gaia at ESA.
“Gaia is uniquely designed to map the celestial objects around us. The mission is building a more detailed and complete view of the Milky Way, and this view is fundamentally changing what we thought we knew about our home galaxy.”
Gaia has revealed that some parts of the Milky Way are far older than expected, and that there have been two key phases of galactic history, the ESA says.
It found that the first phase began less than one billion years after the Big Bang, when stars began to form in a thick disc. A second phase of star formation was triggered two billion years later when the Gaia-Sausage-Enceladus collided with the Milky Way.
Gaia data has also helped astronomers to understand the dwarf galaxies orbiting the Milky Way. It found that one of the closest (the Large Magellanic Cloud) is much bigger than once thought, making up 10% of the mass of the Milky Way.